The paper reports on the observation of phononic helical edge states in a mechanical system, demonstrating the phenomenon of topological insulators in a classical mechanical context. The authors design a lattice of 270 pendula to mimic the quantum spin Hall effect (QSHE) in a quantum mechanical system. They show that the edge modes of the phononic system are helical and robust against imperfections, such as disorder and non-linearities. The edge states are protected by topological properties, similar to those in quantum systems, and can be used as polarizing beam splitters. The study highlights the potential for designing topological acoustic meta-materials with stable surface phonons as reliable wave guides, with applications in acoustic delay lines and other wave-guiding devices. The results bridge the gap between quantum and classical mechanics, providing a foundation for further exploration of topological phenomena in mechanical systems.The paper reports on the observation of phononic helical edge states in a mechanical system, demonstrating the phenomenon of topological insulators in a classical mechanical context. The authors design a lattice of 270 pendula to mimic the quantum spin Hall effect (QSHE) in a quantum mechanical system. They show that the edge modes of the phononic system are helical and robust against imperfections, such as disorder and non-linearities. The edge states are protected by topological properties, similar to those in quantum systems, and can be used as polarizing beam splitters. The study highlights the potential for designing topological acoustic meta-materials with stable surface phonons as reliable wave guides, with applications in acoustic delay lines and other wave-guiding devices. The results bridge the gap between quantum and classical mechanics, providing a foundation for further exploration of topological phenomena in mechanical systems.